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Jurnal Sains Dasar

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Published by Universitas Negeri Yogyakarta

ISSN : 20859872 EISSN : 24431273 DOI : 10.21831

Core Subject : Education,

Education

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Articles 5 Documents

Search results for , issue "Vol 1, No 1 (2012): April 2012" : 5 Documents clear

STUDI PERHITUNGAN HTR PEBBLE-BED DENGAN BERBAGAI MODEL KISI KERNEL DAN KISI PEBBLE Zuhair, Zuhair
Jurnal Sains Dasar Vol 1, No 1 (2012): April 2012
Publisher : Faculty of Mathematics and Natural Science, Universitas Negeri Yogyakarta

In pebble-bed reactor core, lattice models can be changed and even varies with the changing position of pebble. This sort of thing can be found mainly in the area near the vessel wall. Lattice model applied also depends on the procedure how the cylindrical vessel filled. Some lattice models such as SC, BCC, FCC, SH and HCP often used in the high temperature reactor to treat kernel randomness in the graphite matrix and pebble fuel in the reactor core. In this paper a series of calculations of the reactor multiplication factor (keff) conducted with various model of kernel and pebble lattices. The effect of lattice combination which implies on neutronics performance of HTR pebble-bed design is analyzed utilizing the Monte Carlo transport code MCNP5 and continuous energy nuclear data library ENDF/B-VI. MCNP5 calculations show consistency with the keff values which are almost the same for all combinations of kernel and pebble lattices, but if observed further appears that the keff value is more dependent on pebble lattice than kernel lattice kernel. Kernel lattice provides only a less significant effect. The results of keff predictions of all lattice combinations conclude that whatever kernel lattice model utilized, the BCC pebble lattice model is better adopted in the calculation of HTR pebble-bed design with UO2, PuO2 and ThO2/UO2 fuel.

IDENTIFICATION AND BIOLOGICAL ACTIVITY TEST SOME ISOLATED COMPOUNDS FROM STEM BARK OF MELINJO (GNETUM GNEMON) Atun, Sri; Arianingrum, Retno; Masatake, Niwa
Jurnal Sains Dasar Vol 1, No 1 (2012): April 2012
Publisher : Faculty of Mathematics and Natural Science, Universitas Negeri Yogyakarta

Isolation and structure elucidation of two compounds, namely resveratrol (1), and 3- methoxyresveratrol (2) from stem bark of Melinjo (Gnetum gnemon) had been done. The isolation of those compounds was carried out by chromatographyc method and structure elucidation was performed by interpretation of spectroscopic data, including UV, IR, 1H and 13C NMR 1D and 2D, and FABMS. The result of this study showed that activity each compounds as radical hydroxyl scavenger of resveratrol (1), and 3-methoxyresveratrol (2), with an IC50 45,17 and 60,12; g/ml respectively. Each compound showed significant activity as UV-B protection. Activity test as UV-B protection showed that resveratrol and methoxyresveratrol have maximum protections (SPF 8,03 and 12,34 respectively), each compounds on 50 g/ml. Key word : melinjo; Gnetum gnemon; natural antioxidant; UV-B protection

TRANFORMASI POLIMORFIK DAN KARAKTERISASI MIKROSTRUKTUR FASA TiO2 YANG DIHASILKAN MELALUI KALSINASI NANOPITA HIDROGEN TITANAT Hari Sutrisno
Jurnal Sains Dasar Vol 1, No 1 (2012): April 2012
Publisher : Faculty of Mathematics and Natural Science, Universitas Negeri Yogyakarta

Sodium titanates were synthesized by hydrothermal method using Ti(O2)O.2H2O as the starting material in 10 M NaOH at 150°C for 72 h. Hydrogen titanate nanoribbons were obtained by ion exchange of H+ for K+ in sodium titanates by 0.1 M HCl. TiO2 (B), anatase, and anatase-rutile mixture were obtained by the calcinations of hydrogen titanate nanoribbons for 2 h at 500, 700, and 900°c respectively. Hydrogen titanate nanoribbons were characterized by X-rays Diffraction (XRD), High Resolution Scanning Electron Microscopy (HRSEM) and High Resolution Transmition Electron Microscopy (HRTEM). Microstructure of pseudo-TiO2 (B), anatase, and rutile prepared by the calcinations of hydrogen titanates have been determinated in ab initio by the Two Stage Method from powder XRD data. Hydrogen titanates nanoribbons convert into pseudo-TiO2(B) then anatase and finaly rutile structures by heat treatment. Keywords: polymorphic transformation, microstructure characterization, titanium dioxide

UJI KESADAHAN AIR TANAH DI DAERAH SEKITAR PANTAI KECAMATAN REMBANG PROPINSI JAWA TENGAH Sulistyani .; Sunarto .; Annisa Filaeli
Jurnal Sains Dasar Vol 1, No 1 (2012): April 2012
Publisher : Faculty of Mathematics and Natural Science, Universitas Negeri Yogyakarta

Research on soil water hardness,calcium and magnesium covers have been done. Samples were analyzed groundwater in the area around Rembang Coast District Central Java Province. Samples taken from four villages located around the coast and every village three samples taken at random. Samples of water was added HNO3(c), plus the ionization buffer solution, and analyzed using Atomic Absorption Spectrophotometer. Sample concentration is determined using a calibration curve. From the research results can be concluded that the hardness of water wells in the District Rembang remained at normal concentrations far below the dangerous threshold, ie below 200 ppm. Thus, in terms of water hardness district wells in the area especially along the coast of Rembang District is safe to use for everyday purposes and industrial use of fish. From the results of the analysis is also known that the dominant of hardness of water wells in the area is soft water so that the level of hardness can be reduced significantly by means of heating, which can be reduced by 90%.

Peningkatan Efisiensi Sel Surya Berbasis Titania Melalui Penyisipan Logam Besi pada Lapisan Aktif Titania Rita Prasetyowati
Jurnal Sains Dasar Vol 1, No 1 (2012): April 2012
Publisher : Faculty of Mathematics and Natural Science, Universitas Negeri Yogyakarta

Solar cells based on titania was developed continually to reach better performance. To improve the efficiency, titania layer was inserted by Fe metal. Insertion of Fe metal on TiO2 layer has been done by electroplating method with various electroplating voltage and electroplating time duration. Absorption capabilitis of TiO2 was identified by using UV-Vis spectrometer. Morphological structure and composition of materials on TiO2 layer before and after electroplating was identified by SEM (Scanning Electron Microscopy). Structure of solar cells that have been made were characterized by using the I-V meter to determine the performance of solar cells. Solar cell with TiO2 active layer without insertion of Fe only has a solar to electric energy conversion efficiency 0.001%. While solar cells with TiO2 active layer which was inserted Fe have a solar to electric energy conversion efficiency 0.2%. Insertion of Fe on the TiO2 layer formed metal contact layer as a path for electrons to transfer more quickly to the electrode (ITO).

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